The allogenic bone marrow derived mesenchymal stem cells transplantation was given to the newborn girl diagnosed with osteogenesis imperfecta type III, with multiple bone fractures, extreme shortness and limbs deformities. The treatment was performed at the age of 4 and 6 weeks. The clinical diagnosis was supported by biochemical analysis of collagen type I recovered from culture medium of cultivated patient’s skin fibroblast, which revealed its triple helix instability at temperature about 2?C lower than normal. Sequencing of both genes encoding procollagen type I revealed heterozygous substitution G23569Ain COL1A2 gene causing change of glycine at position 517 to aspartate. The donor of mesenchymal stem cells was the girl’s father. She received two intravenous infusions of suspended cultured mesenchymal cells in 16 days apart without any side effects. An analysis of procollagen type I secreted to the culture medium by bone marrow-derived mesenchymal stem cells obtained from the patient, 3 months following transplantation revealed its normal triple helix stability. During the subsequent two years of follow up two new bone fractures were noted. Currently a two-year-old girl’s presents extreme growth and weight deficiency. The motoric development is also retarded, but the patient constantly improves and makes progresses.